If your pet has certain periods where they seem to get unusually loud, it's probably just them doing their thing.
Some animals are naturally excitable. Dogs that bark at even the slightest shifting shadow. Cats that scream at the top of their lungs when it's mealtime.
However, if the volume, pitch, or overall sound of their barks or meows seems to change without rhyme or reason, that could be your first indication that something is amiss. Because a deaf pet cannot hear their own voice, they cannot effectively regulate their volume. A pet with only partial deafness may also face a similar struggle.
Pay close attention to how and when the pet vocalizes, as well. Excessive vocalization is especially common in deaf cats and deaf dogs, though the former tend to become more easily disoriented and upset. If, for example, your cat frequently yowls at night — but the vet can't find anything wrong with them — it may be worth considering the possibility that their ears don't work the way they should.
Of course, there's an equally high possibility that they just love the sound of their voice or can't stand the thought of you spending even two seconds not paying attention to them.